Deposition apparatus for manufacturing thin film

ABSTRACT

A deposition apparatus of the present invention is arranged so that a surface area of a radio-frequency power applying cathode electrode disposed in a glow discharge space, in a space in contact with discharge is greater than a surface area of the whole of a ground electrode (anode electrode) including a beltlike member in the discharge space. 
     This structure can maintain the potential (self-bias) of the cathode electrode disposed in the glow discharge space automatically at a positive potential with respect to the ground (anode) electrode including the beltlike member. 
     As a result, the bias is applied in the direction of irradiation of ions with positive charge to a deposit film on the beltlike member, so that the ions existing in the plasma discharge are accelerated more efficiently toward the beltlike member, thereby effectively giving energy to the surface of deposit film by ion bombardment. Accordingly, since the structural relaxation of film is promoted even at relatively high deposition rates, a microcrystal semiconductor film can be formed at the relatively high deposition rates with good efficiency, with high uniformity, and with good reproducibility.

This application is a division of U.S. application Ser. No. 08/782,811,filed Jan. 13, 1997, now U.S. Pat. No. 5,927,994.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a plasma CVD apparatus for uniformlydepositing a semiconductor thin film on a substrate, with excellentexcellent electric characteristics and to a method for manufacturing athin film. More particularly, the invention relates to a method andapparatus for continuously fabricating a photovoltaic element comprisinga microcrystal thin film on an elongated substrate.

2. Related Background Art

As a method for continuously forming a semiconductor functionaldeposited film, used for photovoltaic elements or the like, on asubstrate, the specification of U.S. Pat. No. 4,400,409 discloses theplasma CVD process employing the roll-to-roll method.

This process is described as being capable of continuously forming anelement having a semiconductor junction by using an elongated beltlikemember as a substrate, and continuously conveying the substrate in thelongitudinal direction thereof while depositing necessaryconductivity-type semiconductor layers hereon in a plurality of glowdischarge regions.

A schematic diagram of a conventional deposition apparatus is shown inFIG. 2. A beltlike member 2000 is conveyed by magnet roller 2005. Whenelectric power is applied between cathode electrode 2002 and anodeelectrode 2004, material gas 2003 is decomposed to generate a plasma ina glow discharge space 2006 and to form a film on the beltlike member2000. In FIG. 2 the arrow 2003 represents the flow of the material gas.

The above apparatus, however, has a problem that it is not easy tomaintain uniform discharge states with good reproducibility during aperiod of several hours for depositing the film over the entire lengthof the elongated substrate.

Further, a light-incident-side doped layer of amorphous silicon solarcell is desirably microcrystallized due to demand for improvement inoptical transparency.

As conventional techniques for forming a microcrystalline p-typesemiconductor layer or n-type semiconductor layer, there are a methodfor mixing phosphine (PH₃), diborane (B₂H₆), or the like as a dopant insilane (SiH₄) or the like being the material gas and for furtherdiluting it with a large amount of hydrogen (H₂) (in the dilution rateof 10 to 100 or more), and a method for applying high radio-frequency(RF) power, but they were not enough to stably form the microcrystallinefilm. The reason is that excitation and decomposition of the materialgas is promoted only in a certain localized portion in the proximity ofthe cathode electrode. Also, these methods consume a lot of bothraw-material gas and power, thus being disadvantageous from a viewpointof cost.

Further, there is another conventional technique for positively applyinga positive potential (bias) to the cathode electrode usingdirect-current (DC) power supply or the like. However, since such asystem employs the secondary means of DC power supply, it is a system topermit direct current to flow into plasma discharge. Therefore, abnormaldischarge such as sparks will occur with increasing DC voltage bias. Itwas thus very difficult to maintain stable discharge as suppressing theabnormal discharge. Accordingly, it was doubtful whether application ofthe DC voltage to the plasma discharge was effective. This is becausethe system is one in which the DC voltage is not separated from thedirect current. In other words, it has been desired to have a means foreffectively applying only the DC voltage to the plasma discharge.

An object of the present invention is to provide a method and depositionapparatus capable of forming a semiconductor thin film which isspatially uniform and and excellent in electric characteristics, withgood reproducibility, and at a high deposition rate.

SUMMARY OF THE INVENTION

The deposition apparatus of the present invention is arranged so that asurface area of an RF power applying cathode electrode disposed in aglow discharge space, in a space in contact with discharge is greaterthan a surface area of the whole of a ground electrode (anode electrode)including a beltlike member in the discharge space.

This solves the problem that excitation and decomposition of materialgas is promoted only in a certain limited portion near the cathodeelectrode, which was the defect in the conventional technology. Namely,the above-stated excitation and decomposition of material gas ispromoted in the entire discharge space, more specifically, on the anodeelectrode side including the beltlike member. As a result, ahigh-quality thin film can be deposited efficiently and at a relativelyhigh deposition rate on the beltlike member.

By this structure, the potential (self-bias) of the cathode electrodedisposed in the glow discharge space can be maintained automatically ata positive potential with respect to the ground (anode) electrodeincluding the beltlike member.

As a result, the bias is applied in the direction of irradiation of thepositively charged ions to the deposited film on the beltlike member,and therefore, the ions existing in the plasma discharge are acceleratedmore efficiently toward the beltlike member. Thus, they effectively giveenergy to the surface of the deposited film by so-called ionbombardment. Therefore, since structural relaxation of the film ispromoted even at relatively high deposition rates, the microcrystallinesemiconductor film can be formed at the relatively high deposition rateswith good efficiency, with high uniformity, and with goodreproducibility.

The method and apparatus of the present invention can be applied notonly to film formation of the light-incident-side doped layer, but alsoto film formation of the i-layer and opposite-side doped layer with thei-layer inbetween. These films do not always have to bemicrocrystallized, but application of the apparatus and method of thepresent invention promotes the structural relaxation more, thuspermitting formation of films with fewer defects.

The potential (self-bias) of the cathode electrode upon glow dischargeis desirably +5 V or more upon deposition of the i-layer and +30 V ormore upon formation of the doped layers. More desirably, it ismaintained at +100 V or more.

Further, the apparatus may be so arranged that it has means capable ofintroducing different gas species independently of each other through aplurality of gas inlet tubes to one film-forming container, at least oneof which is a dedicated inlet tube for supplying a dopant or an additivesuch as germanium, carbon, nitrogen, or oxygen and has structure capableof supplying the dopant or additive to near the surface of the beltlikemember and another of which is for supplying a material gas such assilane becoming a source for forming the film and a diluent gas such ashydrogen and has structure capable of supplying the gases to a regionrelatively apart from the beltlike member.

When the dopant is supplied to near the surface of deposited film, moredoping gas molecules adhere to the surface of the deposited film and theions effectively give energy to the adhering doping gas molecules, whichimproves the doping efficiency of dopant and which, at the same time,enhances the quality and fineness of the film. Therefore, alow-resistance microcrystalline semiconductor thin film can be obtainedrelatively easily.

When the additive is supplied near the surface of the deposited film,more additive gas molecules adhere to the surface of the deposited filmand the ions effectively give energy to the adhering additive gasmolecules, which results in decomposing and activating the additive moreeffectively, so as to promote the structural relaxation of atoms,thereby enhancing the quality and fineness of film.

Examples of the raw-material gas suitable for deposition of the p-layer,n-layer, and i-layer of photovoltaic element of the present inventionare gasifiable compounds containing silicon atoms, gasifiable compoundscontaining germanium atoms, gasifiable compounds containing carbonatoms, etc., and mixtures of gases of the mentioned compounds.

Specific examples of the gasifiable compounds containing silicon atomsare SiH₄, Si₂H₆, SiF₄, SiFH₃, SiF₂H₂, SiF₃H, Si₃H₈, SiD₄, SiHD₃, SiH₂D₂,SiH₃D, SiFD₃, SiF₂D₂, SiD₃H, Si₂D₃H₃, and so on.

Specific examples of the gasifiable compounds containing germanium atomsare GeH₄, GeD₄, GeF₄, GeFH₃, GeF₂H₂, GeF₃H, GeHD₃, GeH₂D₂, GeH_(3D),Ge₂H₆, Ge₂D₆, and so on.

Specific examples of the gasifiable compounds containing carbon atomsare CH₄, CD₄, C_(n)H_(2n+2) (n is an integer), C_(n)H_(2n) (n is aninteger), C₂H₂, C₆H₆, CO₂, CO, and so on.

Examples of gas containing nitrogen atoms are N₂, NH₃, ND₃, NO, NO₂, andN₂O.

Examples of gas containing oxygen atoms are O₂, CO, CO₂, NO, NO₂, N₂O,CH₃CH₂OH, CH₃OH, and so on.

Examples of the substance introduced into the p-type layer or the n-typelayer in order to control the valence electrons in the present inventionare the atoms in Group III and the atoms in Group V in the periodictable.

Materials effectively used as a starting substance for introduction ofthe atoms in Group III in the present invention, specifically forintroduction of boron atoms, are boron hydrides such as B₂H₆, B₄H₁₀,B₅H₉, B₅H₁₁, B₆H₁₀, B₆H₁₂, and B₆H₁₄, boron halides such as BF₃ andBCl₃, and so on. Additional examples are AlCl₃, GaCl₃, InCl₃, TlCl₃, andso on. Particularly, B₂H₆ and BF₃ are suitable.

Materials effectively used as a starting substance for introduction ofthe atoms in Group V in the present invention, specifically forintroduction of phosphorus atoms, are phosphorus hydrides such as PH₃and P₂H₄, phosphorus halides such as PH₄I, PF₃, PF₅, PCl₃, PCl₃, PBr₃,PBr₅, and PI₃, and so on. In addition, other examples are AsH₃, AsF₃,AsCl₃, AsBr₃, AsF₅, SbH₃, SbF₃, SbF₅, SbCl₃, SbCl₅, BiH₃, BiCl₃, BiBr₃,and so on. Particularly, PH₃ and PF₃ are suitable.

Further, the foregoing gasifiable compounds may be introduced into adeposition chamber as being diluted properly with a gas such as H₂, He,Ne, Ar, Xe, or Kr.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a conceptual schematic drawing to show an example of thedischarge space in the deposited film forming apparatus using thecathode electrode of the present invention;

FIGS. 1B, 1C, 1D, 1E, 1F and 1G are conceptual schematic drawings eachof which shows another example of the cathode electrode of the presentinvention;

FIG. 2 is a conceptual schematic drawing to show an example of thedischarge space of the photovoltaic element manufacturing apparatususing the conventional cathode electrode;

FIG. 3 is an example of a photovoltaic element manufacturing apparatusof the roll-to-roll method employing the method of the presentinvention;

FIG. 4 is a cross-sectional view of a single type photovoltaic element;

FIG. 5 is a cross-sectional view of a triple type photovoltaic element;

FIG. 6 is a cross-sectional view of a deposit film forming apparatus ofthe present invention;

FIG. 7 is an example of the cathode electrode of the present invention;and

FIGS. 8A and 8B are cross-sectional views of a deposit film formingapparatus of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The apparatus and method of the present invention will be described withreference to the drawings, but it is noted that the present invention isby no means limited to these. Apparatus Example 1

FIG. 1A is a schematic drawing to show the feature in the dischargecontainer of the present invention. It is constructed so that thecathode electrode 1002 having the same structure as the example of thecathode electrode shown in FIG. 1E is set as electrically insulated onthe ground (anode) electrode 1004 and that an electroconductive beltlikemember 1000 moves in the direction of the arrow 1003 without physicalcontact with the lower cathode electrode and with the anode electrode asbeing supported by a plurality of magnet rollers above the cathodeelectrode.

A material suitably applicable for the cathode electrode and anodeelectrode is stainless steel or aluminum.

The material gas flows in the direction of arrows as passing through thespace between partitions of the cathode electrode and is then evacuatedby an unrepresented evacuation apparatus.

RF power is supplied from an unrepresented RF power supply to thecathode electrode. The discharge region of glow discharge induced is thespace between the partitions of the cathode electrode, which is a regionconfined by the upper electroconductive beltlike member.

In the case of use of the discharge container in such structure, theratio of the area of the cathode electrode to the area of the groundanode electrode including the beltlike member is clearly greater than 1.

The configuration of the cathode electrode of the present invention isnot limited to this, and some other examples will be shown.

FIG. 1B, FIG. 1C, FIG. 1D, FIG. 1E, FIG. 1F, and FIG. G show examples ofschematic views of configurations of the cathode electrode, used in themethod and apparatus of-the present invention.

FIG. 1B is an example wherein the cross section of the cathodeconfiguration is of a U-shape.

FIG. 1C is an example of structure in which a plurality of fin-shapedpartitions are provided along the direction perpendicular to theconveying direction of the beltlike member. It is the structure in whicha plurality of vents or gas passing holes 1010 for letting the materialgas pass are provided in the partitions. The gas passing holes may beformed so as to have the size for permitting the material gas to passand so as not to damage the function as a cathode electrode and they maybe formed as in an example of structure shown in FIG. 1D, for example.In FIG. 1D, numeral 1011 designates gas passing holes.

FIG. 1E shows an example of structure in which a plurality of fin-shapedpartitions are provided in parallel with the conveying direction of thebeltlike member.

FIGS. 1F and 1G show examples wherein the partitions are of a blockshape and a cross section thereof is of a chevron shape. Theseconfigurations of the cathode electrode can be formed by cutting.

Alternatively, they may be formed by bending a flat plate in the chevronshape.

Example 1 (Single Cell) of Fabrication of Photovoltaic Element

The discharge container as shown in FIG. 1A was used for fabrication ofthe p-layer and n-layer of a pin type photovoltaic element. The ratio ofthe area of the cathode to the overall area of the ground anodeincluding the electroconductive beltlike member was 1.5.

FIG. 3 is a schematic drawing of the manufacturing apparatus. Thisexample of the manufacturing apparatus is comprised of vacuum containers301 and 302 for delivery and for winding of the beltlike member 101, avacuum container 601 for fabrication of the first-conductivity-typelayer, a vacuum container 100 for fabrication of the i-type layer, and avacuum container 602 for fabrication of the second-conductivity-typelayer, connected through a gas gate.

In FIG. 3, numerals 307 and 308 designate conductance valves; 124 n, 124and 124 p lamp heaters; 603 and 107 cathode electrodes; 314 and 315pressure gauges; 605 and 606 gas inlet tubes; and 513 and 608 exhausttubes.

The structure of the cathode electrode 603 in the vacuum container 601and the cathode electrode 604 in the vacuum container 602 was the samecathode electrode structure as described above.

Using the manufacturing apparatus shown in FIG. 3, thefirst-conductivity-type layer, i-type layer, andsecond-conductivity-type layer were successively deposited on the lowerelectrode under the fabrication conditions shown in Table 1 and inaccordance with the fabrication procedures described below, therebycontinuously fabricating the single type photovoltaic element (Elem-Ex1).

First set in the vacuum container 301 having a substrate deliverymechanism was a bobbin 303 on which the beltlike member 101 (120 mmwide×200 m long×0.13 mm thick), made of SUS430BA sufficiently degreasedand cleaned and having a silver thin film 100 nm thick and a ZnO thinfilm 1 μm thick deposited as a lower electrode by sputtering, was wound;then the beltlike member 101 was passed through the gas gates 129 n,129, 130, 129 p and the vacuum containers for fabrication of therespective non-monocrystal layers up to the vacuum container 302 havinga beltlike member winding mechanism; and the tension thereof wasadjusted so as to eliminate slack.

The beltlike member may be one obtained by forming an electroconductivethin film of aluminum or the like on a heat-resistant resin such aspolyimide.

Next, each vacuum container 301, 601, 100, 602, 302 was vacuumized downto 1×10⁻⁴ or less Torr by an unrepresented vacuum pump.

Next, H₂ as a gate gas was introduced at 700 sccm through a gate gasinlet tube 131 n, 131, 132, 131 p to each gas gate.

The substrate temperature, gas flow rate, and pressure in each vacuumchamber were set in the conditions of Table 1.

Next, the RF power was supplied under the conditions of Table 1 to thecathode electrode 603 in each deposition chamber.

Next, the beltlike member 101 was conveyed in the direction of arrows inthe drawing, so that the first-conductivity-type layer, i-type layer,and second-conductivity-type layer were made on the beltlike member.

Next, ITO (In₂O₃+SnO₂) was evaporated in the thickness of 80 nm as atransparent electrode over the second-conductivity-type layer by vacuumvapor deposition, and further, Al was evaporated in the thickness of 2μm as a collector electrode by vacuum vapor deposition, thus preparingthe photovoltaic element.

A cross section of the element is shown in FIG. 4.

TABLE 1 Substrate: SUS430BA 0.13 mm thick Reflective layer: Silver (Ag)thin film 100 nm Reflection enhancing layer: Zinc oxide (ZnO) thin film1 μm Gate gas: 700 sccm from each gate Used Thick- Gas and Sub- ness ofFlow RF Pres- strate Name of Layer Rate Power sure Temp. Layer (nm)(sccm) (W) (Torr) (° C.) 1st- 40 SiH₄ 40 500 1.5 350 conduc- PH₃/H₂tivity 50 type (2% dil) layer H₂ 500 i-type 150 SiH₄ 200 1.8 350 layer100 each H₂ 500 each 2nd- 20 SiH₄ 10 500 1.6 200 conduc- BF₃/H₂ tivity100 type (2% dil) layer H₂ 2000 Transparent electrode: ITO (In₂O₃ +SnO₂) thin film 80 nm Collector electrode: Aluminum (Al) thin film 2 μm

COMPARATIVE EXAMPLE 1

The structure of the cathode electrode 603 in the vacuum container 601and the cathode electrode 604 in the vacuum container 602 was theconventional cathode electrode structure shown in FIG. 2. Namely, theratio of the area of the cathode to the total area of the ground anodeincluding the electroconductive beltlike member was 0.6.

A single type photovoltaic element was fabricated according to the sameprocedures as in Example 1 except that the fabrication conditions wereas shown in Table 2 (Elem-Comp 1).

TABLE 2 Substrate: SUS430BA 0.13 mm thick Reflective layer: Silver (Ag)thin film 100 nm Reflection enhancing layer: Zinc oxide (ZnO) thin film1 μm Gate gas: 700 sccm from each gate Used Thick- Gas and Sub- ness ofFlow RF Pres- strate Name of Layer Rate Power sure Temp. Layer (nm)(sccm) (W) (Torr) (° C.) 1st- 40 SiH₄ 40 800 1.5 350 conduc- PH₃/H₂tivity 50 type (2% dil) Layer H₂ 500 i-type 150 SiH₄ 200 1.8 350 layer100 each H₂ 500 each 2nd- 20 SiH₄ 10 800 1.6 200 conduc- BF₃/H₂ tivity100 type (2% dil) Layer H₂ 2000 Transparent electrode: ITO (In₂O₃ +SnO₂) thin film 80 nm Collector electrode: Aluminum (Al) thin film 2 μm

Cross-sectional TEM images were observed of the photovoltaic elementsfabricated in Example 1 (Elem-Ex 1) and in Comparative Example 1(Elem-Comp 1). As a result, microcrystal grains were observed withElem-Ex 1, but were not observed with Elem-Comp 1. A conceivable reasonof this is that in the present invention the self-bias of the cathode ispositive because of the large ratio of the cathode area to the totalanode area, which promoted microcrystallization.

Experiments were conducted to check the relation of self-bias of cathodeversus ratio of cathode area to anode area. In the cathode electrode ofthe configuration as shown in FIG. 1E, the number and size of pluralpartitions provided in parallel or perpendicularly to the conveyingdirection of the beltlike member were charged so as to change the ratioof the surface area of the cathode electrode to the anode area between1.00 and 2.00, while the values of the self-bias occurring in thecathode electrode were also checked. The results are shown in Table 3.

TABLE 3 Ratio of cathode area to Self-bias of cathode anode areaelectrode (%) (V) 60 −140 100  −20 110  +30 120  +40 150  +90 200 +190

After the ratio of the cathode area to the anode area exceedsapproximately 100%, the potential (self-bias) of the cathode electrodeis found to become positive (or plus).

In order to evaluate the effect of microcrystallization of the depositedfilm, areas 5 cm square were cut out at intervals of 10 m from each ofElem-Ex 1 and Elem-Comp 1 and were subjected to evaluation of conversionefficiency, characteristic uniformity, and yield.

Current-voltage characteristics were evaluated by setting the elementsunder irradiation of AM-1.5 (100 mW/cm²) light and measuring theirphotoelectric conversion factors. The results are shown in Table 4. Eachvalue is a relative value when each characteristic of Elem-Comp 1 isreferenced to 1.00. The characteristics of Elem-Ex 1 were totallyimproved as compared with those of Elem-Comp 1, and especially, animprovement in open-circuit voltage resulted in an improvement of 1.07times the conversion efficiency.

TABLE 4 Selfbias upon Selfbias upon form of 1st- form of 2nd- Microconductivity conductivity Open- Elem. crystal type type Conversioncircuit Current No. grain layer (V) layer (V) Efficiency Voltage DensityF.F. Elem- Yes +100 +110 1.07 1.05 1.01 1.01 Ex 1 Elem- No −150 −1601.00 1.00 1.00 1.00 Comp 1

Next evaluated was the dispersion of photoelectric conversionefficiency. The reciprocal of magnitude of dispersion was obtained withreference to the photovoltaic element of Comparative Example 1(Elem-Comp 1).

The yield was evaluated by measuring shunt resistance in a darkcondition, counting elements with resistance values not less than 1×10³Ω·cm² as non-defective, and obtaining a percentage of non-defectiveelements in the total number.

TABLE 5 Dispersion of conversion Element No. efficiency Yield (%)Elem-Ex 1 1.18 98 Elem-Comp 1 1.00 94

As shown in Table 4, the photovoltaic element of Example 1 (Elem-Ex 1)was superior in both characteristic uniformity and yield to thephotovoltaic element of Comparative Example 1 (Elem-Comp 1), so that thesingle type photovoltaic element fabricated by the fabrication method ofthe present invention was found to have the excellent characteristics,thus proving the effect of the present invention.

Example 2 (Triple Cell) of Fabrication of Photovoltaic Element

Defining as one set a system in which the vacuum container 601 forfabrication of the first-conductivity-type layer, the vacuum container100 for fabrication of the i-type layer, and the vacuum container 602for fabrication of the second-conductivity-type layer were connectedthrough a gas gate, two more sets were added so as to make a system insuch an arrangement that the three sets in total were repetitivelyarranged in series, in which the cathode electrode structure of the allfirst-conductivity-type layer forming containers and thesecond-conductivity-type layer forming containers was the above-statedcathode electrode structure. Using such a system, the triple typephotovoltaic element (Elem-Ex 2) was fabricated.

The fabrication conditions of the photovoltaic element are shown inTable 6.

TABLE 6 Substrate: SUS430BA 0.13 mm thick Reflective layer: Silver (Ag)thin film 100 nm Reflection enhancing layer: Zinc oxide (ZnO) thin film1 μm Gate gas: 700 sccm from each gate Used Thick- Gas and Sub- ness ofFlow RF Pres- strate Name of Layer Rate Power sure Temp. Layer (nm)(sccm) (W) (Torr) (° C.) 1st- 40 SiH₄ 40 500 1.5 350 conduc- PH₃/H₂tivity 50 type (2% dil) layer H₂ 500 1st i- 100 SiH₄ 50 200 1.8 350 typeeach layer GeH₄ 50 each H₂ 500 each 2nd- 20 SiH₄ 10 500 1.6 200 conduc-BF₃/H₂ tivity 100 type (2% dil) layer H₂ 2000 1st- 40 SiH₄ 40 500 1.5350 conduc- PH₃/H₂ tivity 50 type (2% dil) layer H₂ 500 2nd i- 100 SiH₄60 200 1.8 350 type each layer GeH₄ 40 each H₂ 500 each 2nd- 20 SiH₄ 10500 1.6 200 conduc- BF₃/H₂ tivity 100 type (2% dil) layer H₂ 2000 1st-40 SiH₄ 40 500 1.5 350 conduc- PH₃/H₂ tivity 50 type (2% dil) layer H₂500 3rd i- 90 SiH₄ 200 1.8 200 type 100 layer each H₂ 500 each 2nd- 20SiH₄ 10 500 1.6 200 conduc- BF₃/H₂ tivity 100 type (2% dil) layer H₂2000 Transparent electrode: ITO (In₂O₃ + SnO₂) thin film 80 nm Collectorelectrode: Aluminum (Al) thin film 2 μm

COMPARATIVE EXAMPLE 2

A triple type photovoltaic element was fabricated in the same proceduresas those in Example 2 except that the cathode electrode structure forthe first-conductivity-type layers and the second-conductivity-typelayers was the cathode electrode structure shown in FIG. 2 (in thiscase, the ratio of the cathode area to the total area of the groundanode including the electroconductive beltlike member was 0.6) and thatthe fabrication conditions as shown in Table 7 were employed (Elem-Comp2).

TABLE 7 Substrate: SUS430BA 0.13 mm thick Reflective layer: Silver (Ag)thin film 100 nm Reflection enhancing layer: Zinc oxide (ZnO) thin film1 μm Gate gas: 700 sccm from each gate Used Thick- Gas and Sub- ness ofFlow RF Pres- strate Name of Layer Rate Power sure Temp. Layer (nm)(sccm) (W) (Torr) (° C.) 1st- 40 SiH₄ 40 800 1.5 350 conduc- PH₃/H₂tivity 50 type (2% dil) layer H₂ 500 1st i- 100 SiH₄ 50 200 1.8 350 typeeach layer GeH₄ 50 each H₂ 500 each 2nd- 20 SiH₄ 10 800 1.6 200 conduc-BF₃/H₂ tivity 100 type (2% dil) layer H₂ 2000 1st- 40 SiH₄ 40 800 1.5350 conduc- PH₃/H₂ tivity 50 type (2% dil) layer H₂ 500 2nd i- 100 SiH₄60 200 1.8 350 type each layer GeH₄ 40 each H₂ 500 each 2nd- 20 SiH₄ 10800 1.6 200 conduc- BF₃/H₂ tivity 100 type (2% dil) layer H₂ 2000 1st-40 SiH₄ 40 800 1.5 350 conduc- PH₃/H₂ tivity 50 type (2% dil) layer H₂500 3rd i- 90 SiH₄ 200 1.8 200 type 100 layer each H₂ 500 each 2nd- 20SiH₄ 10 800 1.6 200 conduc- BF₃/H₂ tivity 100 type (2% dil) layer H₂2000 Transparent electrode: ITO (In₂O₃ + SnO₂) thin film 80 nm Collectorelectrode: Aluminum (Al) thin film 2 μm

Evaluation of the conversion efficiency, characteristic uniformity, andyield was carried out in the same manner as in Example 1 for thephotovoltaic elements fabricated in Example 2 (Elem-Ex 2) andComparative Example 2 (Elem-Comp 2).

TABLE 8 Self- Self- bias bias upon upon form form of of 1st- 2nd-conduc- conduc- tivity tivity Conver- type type sion Open- Elem. layerslayers Effi- circuit Current No. (V) (V) ciency Voltage Density F.F.Elem- +100 +110 1.06 1.04 1.01 1.01 Ex 2 Elem- −150 −160 1.00 1.00 1.001.00 Comp 2

TABLE 9 Dispersion of conversion Element No. efficiency Yield (%)Elem-Ex 2 1.17 99 Elem-Comp 2 1.00 94

As shown in Table 8 and Table 9, the photovoltaic element of Example 2(Elem-Ex 2) was superior in both characteristic uniformity and yield tothe photovoltaic element of Comparative Example 2 (Elem-Comp 2), so thatthe triple type photovoltaic element fabricated by the fabricationmethod of the present invention was found to have the excellentcharacteristics, thus proving the effect of the present invention.

Examples 3 to 6 of Fabrication of Photovoltaic Element (Examination ofDeposition Rate)

The flow rate of SiH₄ gas introduced into the first-conductivity-typelayer forming container was changed in the range of from 30 to 60 sccm,thereby changing the deposition rate. Single type photovoltaic elementswere fabricated in the same procedures as in Example 1 except for theabove point and except that the fabrication conditions as shown in Table10 were employed (Elem-Ex 3 to 6).

TABLE 10 Substrate: SUS430BA 0.13 mm thick Reflective layer: Silver (Ag)thin film 100 nm Reflection enhancing layer: Zinc oxide (ZnO) thin film1 μm Gate gas: 700 sccm from each gate Used Thick- Gas and Sub- ness ofFlow RF Pres- strate Name of Layer Rate Power sure Temp. Layer (nm)(sccm) (W) (Torr) (° C.) 1st- 40 SiH₄ 500 1.5 350 conduc- 30-60 tivityPH₃/H₂ type 50 layer (2% dil) H₂ 500 i-type 150 SiH₄ 200 1.8 350 layer100 each H₂ 500 each 2nd- 20 SiH₄ 10 500 1.6 200 conduc- BF₃/H₂ tivity100 type (2% dil) layer H₂ 2000 Transparent electrode: ITO (In₂O₃ +SnO₂) thin film 80 nm Collector electrode: Aluminum (Al) thin film 2 μm

At the same time as it, values of the self-bias occurring in the cathodeelectrode were also checked and connection thereof with thecharacteristics of photovoltaic element was evaluated. The filmthickness of the first-conductivity-type layer was kept constant at 40nm even under any conditions by adjusting the aperture length of thedischarge space.

COMPARATIVE EXAMPLES 3 to 6

Single type photovoltaic element were fabricated in the same proceduresas those in Example 3 except that the electrode structure of the cathodeelectrode for the first-conductivity-type layer was the cathodeelectrode structure shown in FIG. 2 (in this case, the ratio of thecathode area to the total area of the ground anode including theelectroconductive beltlike member was 0.6) and that the fabricationconditions as shown in Table 11 were employed (Elem-Comp 3 to 6).

TABLE 11 Substrate: SUS430BA 0.13 mm thick Reflective layer: Silver (Ag)thin film 100 nm Reflection enhancing layer: Zinc oxide (ZnO) thin film1 μm Gate gas: 700 sccm from each gate Used Thick- gas and Sub- ness ofFlow RF Pres- strate Name of Layer Rate Power sure Temp. Layer (nm)(sccm) (W) (Torr) (° C.) 1st- 40 SiH₄ 800 1.5 350 conduc- 30-60 tivityPH₃/H₂ type 50 layer (2% dil) H₂ 500 i-type 150 SiH₄ 200 1.8 350 layer100 each H₂ 500 each 2nd- 20 SiH₄ 10 800 1.6 200 conduc- BF₃/H₂ tivity100 type (2% dil) layer H₂ 2000 Transparent electrode: ITO (In₂O₃ +SnO₂) thin film 80 nm Collector electrode: Aluminum (Al) thin film 2 μm

Results of measurement and evaluation of photoelectric conversionefficiency are shown in Table 12. Each value is an arbitrary value wheneach characteristic of Elem-Comp 3 is referenced to 1.00.

TABLE 12 Deposition rate of Self-bias 1st- of 1st- conduc- conduc-tivity tivity Conver- type type Open- sion Element layer layer circuitEffi- No. (Å/sec) (V) Voltage ciency Elem-Ex 3 0.6 +110 1.02 1.03Elem-Ex 4 1.0 +108 1.02 1.03 Elem-Ex 5 1.2 +104 1.01 1.02 Elem-Ex 6 1.5+102 1.01 1.02 Elem-Comp 3 0.6 −160 1.00 1.00 Elem-Comp 4 1.0 −155 0.990.99 Elem-Comp 5 1.2 −150 0.95 0.95 Elem-Comp 6 1.5 −146 0.93 0.93

The open-circuit voltages of Elem-Ex 3 to 6 are totally improved ascompared with Elem-Comp 3 and as a result, the conversion factors areimproved. Especially, where the ratio of the cathode electrode area isset large (Elem-Ex 3 to 6), drops of characteristics can be restrictedeven at the large deposition rates of not less than 1 Å/sec. On theother hand, where the ratio of the cathode electrode area is set small(Elem-Com 3 to 6), the open-circuit voltages drop with increasing thedeposition rates, which decreases the conversion efficiency.

As shown in Table 12, the photovoltaic elements of Example 4 (Elem-Ex 3to 6) are superior in the conversion efficiency to those of ComparativeExample 4 (Elem-Comp 3 to 6), and it was found that as long as thephotovoltaic elements were fabricated under the conditions that thecathode area was greater than the anode area and that the self-bias wasof a positive potential, the photovoltaic elements would have excellentcharacteristics even with increasing deposition rates, thus proving theeffect of the present invention.

Example 7 of Fabrication of Photovoltaic Element (Example of Applicationto the i-layer)

The discharge container as shown in FIG. 1A was used for fabrication ofthe i-layer of a pin type photovoltaic element (Elm-Ex 7). The ratio ofthe area of the cathode to the overall area of the ground anodeincluding the electroconductive beltlike member was 1.5.

The fabrication conditions are shown in Table 13.

TABLE 13 Substrate: SUS430BA 0.13 mm thick Reflective layer: Silver (Ag)thin film 100 nm Reflection enhancing layer: Zinc oxide (ZnO) thin film1 μm Gate gas: 700 sccm from each gate Used Thick- Gas and Sub- ness ofFlow RF Pres- strate Name of Layer Rate Power sure Temp. Layer (nm)(sccm) (W) (Torr) (° C.) 1st- 40 SiH₄ 40 800 1.5 350 conduc- PH₃/H₂tivity 50 type (2% dil) layer H₂ 500 i-type 140 SiH₄ 80 100 1.8 300layer H₂ 200 2nd- 20 SiH₄ 10 800 1.6 250 conduc- BF₃/H₂ tivity 100 type(2% dil) layer H₂ 2000 Transparent electrode: ITO (In₂O₃ + SnO₂) thinfilm 80 nm Collector electrode: Aluminum (Al) thin film 2 μm

COMPARATIVE EXAMPLE 7

A single type photovoltaic element was fabricated in the same proceduresas those in Example 7 except that the electrode structure of the cathodeelectrode for the i-layer was the cathode electrode structure shown inFIG. 2 (in this case, the ratio of the cathode area to the total area ofthe ground anode including the electroconductive beltlike member was0.6) and that the fabrication conditions as shown in Table 14 wereemployed (Elem-Comp 7).

TABLE 14 Substrate: SUS430BA 0.13 mm thick Reflective layer: Silver (Ag)thin film 100 nm Reflection enhancing layer: Zinc oxide (ZnO) thin film1 μm Gate gas: 700 sccm from each gate Used Thick- Gas and Sub- ness ofFlow RF Pres- strate Name of Layer Rate Power sure Temp. Layer (nm)(sccm) (W) (Torr) (° C.) 1st- 40 SiH₄ 40 800 1.5 350 conduc- PH₃/H₂tivity 50 type (2% dil) layer H₂ 500 i-type 140 SiH₄ 200 1.8 300 layer100 H₂ 500 2nd- 20 SiH₄ 10 800 1.6 250 conduc- BF₃/H₂ tivity 100 type(2% dil) layer H₂ 2000 Transparent electrode: ITO (In₂O₃ + SnO₂) thinfilm 80 nm Collector electrode: Aluminum (Al) thin film 2 μm

Evaluation of the conversion efficiency, characteristic uniformity, andyield was carried out in the same manner as in Example 1 for thephotovoltaic elements fabricated in Example 7 (Elem-Ex 7) andComparative Example 7 (Elem-Comp 7).

TABLE 15 Self- bias upon form Conver- of i-type sion Open- Elem. layerEffi- circuit Current No. (V) ciency Voltage Density F.F. Elem- +18 1.031.01 1.01 1.01 Ex 7 Elem- −55 1.00 1.00 1.00 1.00 Comp 7

TABLE 16 Dispersion of conversion Element No. efficiency Yield (%)Elem-Ex 7 1.07 99 Elem-Comp 7 1.00 96

As shown in Table 15 and Table 16, the photovoltaic element of Example 7(Elem-Ex 7) was superior in both characteristic uniformity and yield tothe photovoltaic element of Comparative Example 7 (Elem-Comp 7), so thatthe single type photovoltaic element fabricated by the fabricationmethod of the present invention was found to have the excellentcharacteristics, thus proving the effect of the present invention.

Examples 8 to 11 of Fabrication of Photovoltaic Element (Examination ofDeposition Rate)

The flow rate of SiH₄ gas introduced into the i-layer forming containerwas changed in the range of from 60 to 100 sccm, thereby changing thedeposition rate. Single type photovoltaic elements were fabricated inthe same procedures as in Example 7 except for the above point andexcept that the fabrication conditions as shown in Table 17 wereemployed (Elem-Ex 8 to 11).

TABLE 17 Substrate: SUS430BA 0.13 mm thick Reflective layer: Silver (Ag)thin film 100 nm Reflection enhancing layer: Zinc oxide (ZnO) thin film1 μm Gate gas: 700 sccm from each gate Used Thick- Gas and Sub- ness ofFlow RF Pres- strate Name of Layer Rate Power sure Temp. Layer (nm)(sccm) (W) (Torr) (° C.) 1st- 40 SiH₄ 40 800 1.5 350 conduc- PH₃/H₂tivity 50 type (2% dil) layer H₂ 500 i-type 140 SiH₄ 80 to 1.8 300 layer60 to 120 100 H₂ 200 2nd- 20 SiH₄ 10 800 1.6 250 conduc- BF₃/H₂ tivity100 type (2% dil) layer H₂ 2000 Transparent electrode: ITO (In₂O₃ +SnO₂) thin film 80 nm Collector electrode: Aluminum (Al) thin film 2 μm

At the same time as it, values of the self-bias occurring in the cathodeelectrode were also checked and connection thereof with thecharacteristics of photovoltaic element was evaluated.

COMPARATIVE EXAMPLES 8 to 11

Single type photovoltaic elements were fabricated in the same proceduresas those in Example 8 except that the electrode structure of the cathodeelectrode for the i-layer was the cathode electrode structure shown inFIG. 2 (in this case, the ratio of the cathode area to the total area ofthe ground anode including the electroconductive beltlike member was0.6) and that the fabrication conditions as shown in Table 18 wereemployed (Elem-Comp 8 to 11).

TABLE 18 Substrate: SUS430BA 0.13 mm thick Reflective layer: Silver (Ag)thin film 100 nm Reflection enhancing layer: Zinc oxide (ZnO) thin film1 μm Gate gas: 700 sccm from each gate Used Thick- Gas and Sub- ness ofFlow RF Pres- strate Name of Layer Rate Power sure Temp. Layer (nm)(sccm) (W) (Torr) (° C.) 1st- 40 SiH₄ 40 800 1.5 350 conduc- PH₃/H₂tivity 50 type (2% dil) layer H₂ 500 i-type 140 SiH₄ 180 to 1.8 300layer 80 to 220 120 H₂ 500 2nd- 20 SiH₄ 10 800 1.6 250 conduc- BF₃/H₂tivity 100 type (2% dil) layer H₂ 2000 Transparent electrode: ITO(In₂O₃ + SnO₂) thin film 80 nm Collector electrode: Aluminum (Al) thinfilm 2 μm

Results of measurement and evaluation of photoelectric conversionefficiency are shown in Table 19. Each value is a relative value whenthe characteristic of Elem-Comp 8 is referenced to 1.00.

TABLE 19 Self-bias upon Deposi- discharge tion rate for i- Conver- ofi-type type sion Element layer layer Effi- No. (Å/sec) (V) ciencyElem-Ex 8 0.6 +5 1.03 Elem-Ex 9 1.0 +10 1.03 Elem-Ex 1.2 +16 1.02 10Elem-Ex 1.5 +19 1.02 11 Elem-Comp 0.6 −26 1.00 8 Elem-Comp 1.0 −29 0.999 Elem-Comp 1.2 −32 0.95 10 Elem-Comp 1.5 −36 0.93 11

The open-circuit voltages of Elem-Ex 8 to 11 are totally improved ascompared with Elem-Comp 8 and as a result, the conversion factors areimproved. Especially, where the ratio of the cathode electrode area isset large (Elem-Ex 8 to 11), drops of characteristics can be restrictedeven at the large deposition rates. On the other hand, where the ratioof the cathode electrode area is set small (Elem-Comp 8 to 11), theopen-circuit voltages drop with increasing deposition rates, whichdecreases the conversion efficiencies.

As shown in Table 19, the photovoltaic elements of Examples 8-11(Elem-Ex 8 to 11) are superior in the conversion efficiency to those ofComparative Examples 8-11 (Elem-Comp 8 to 11), and it was found that aslong as the photovoltaic elements were fabricated under the conditionsthat the cathode area was greater than the anode area and that theself-bias was of a positive potential, the photovoltaic elements wouldhave excellent characteristics even with increasing deposition rates,thus proving the effect of the present invention.

Examples 12 to 22 of Fabrication of Photovoltaic Element.

Examined herein were the spacing between the cathode electrode and thesubstrate and the spacing between fins of the cathode electrode.Referring to FIG. 6, in a deposition chamber 6001 through which anelongated substrate 6000 passes there are provided cathode electrode6002 having fins 6003, ground anode electrode 6004, and heater 6005. Theraw-material gas was supplied from a gas supply tube 6007 and evacuatedthrough an exhaust tube 6006. The configuration of the cathode electrodeis shown in FIG. 7.

The spacing between the cathode electrode 6002 and the substrate 6000 isrepresented by L1, and the spacing between the fins by L2.

This apparatus was used for fabrication of the p-layer of single cell.The fabrication conditions are shown in Table 20.

TABLE 20 Substrate: SUS430BA 0.13 mm thick Reflective layer: Silver (Ag)thin film 100 nm Reflection enhancing layer: Zinc oxide (ZnO) thin film1 μm Gate gas: 700 sccm from each gate Used Thick- Gas and Sub- ness ofFlow RF Pres- strate Name of Layer Rate Power sure Temp. Layer (nm)(sccm) (W) (Torr) (° C.) 1st- 40 SiH₄ 40 800 1.5 350 conduc- PH₃/H₂tivity 50 type (2% dil) layer H₂ 500 i-type 140 SiH₄ 200 1.8 300 layer100 each H₂ 500 each 2nd- 20 SiH₄ 10 600 1.6 250 conduc- BF₃/H₂ tivity100 type (2% dil) layer H₂ 500 Transparent electrode: ITO(In₂O_(3 + SnO) ₂) thin film 80 nm Collector electrode: Aluminum (Al)thin film 2 μm

COMPARATIVE EXAMPLE 12

With the conventional apparatus shown in FIG. 2, a single cell wasfabricated under the conditions shown in Table 21.

TABLE 21 Substrate: SUS430BA 0.13 mm thick Reflective layer: Silver (Ag)thin film 100 nm Reflection enhancing layer: Zinc oxide (ZnO) thin film1 μm Gate gas: 700 sccm from each gate Used Thick- Gas and Sub- ness ofFlow RF Pres- strate Name of Layer Rate Power sure Temp. Layer (nm)(sccm) (W) (Torr) (° C.) 1st- 40 SiH₄ 40 800 1.5 350 conduc- PH₃/H₂tivity 50 type (2% dil) layer H₂ 500 i-type 140 SiH₄ 200 1.8 350 layer100 each H₂ 500 each 2nd- 10 SiH₄ 10 800 1.6 250 conduc- BF₃/H₂ tivity100 type (2% dil) layer H₂ 2000 Transparent electrode: ITO (In₂O₃ +SnO₂) thin film 80 nm Collector electrode: Aluminum (Al) thin film 2 μm

The conversion efficiency, open-circuit voltage, current density, andfill factor were measured for the elements (Elem-Ex 12 to 16) aschanging the spacing L1 between the cathode electrode and the substratefrom 0.2 to 6 cm.

TABLE 22 Con- ver- Open- sion cir- Cur- Space Effi- cuit rent Elem. L1cien- Volt- Den- No. (cm) cy age sity F.F. Elem-   0.2 1.05 1.03 1.011.01 Ex 12 Elem- 1 1.04 1.02 1.01 1.01 Ex 13 Elem- 3 1.03 1.01 1.01 1.01Ex 14 Elem- 5 1.03 1.01 1.01 1.01 Ex 15 Elem- 6 1.01 1.00 1.00 1.00 Ex16 Elem- — 1.00 1.00 1.00 1.00 Comp 12

Similar data was measured for the elements (Elem-Ex 17 to 22) aschanging the spacing between the fins of the cathode electrode from 1 to12 cm.

TABLE 23 Con- ver- Open- sion cir- Cur- Space Effi- cuit rent Elem. L2cien- Volt- Den- No. (cm) cy age sity F.F. Elem- 1 1.01 1.00 1.00 1.00Ex 17 Elem- 2 1.03 1.01 1.01 1.01 Ex 18 Elem- 4 1.05 1.03 1.01 1.01 Ex19 Elem- 7 1.04 1.02 1.01 1.01 Ex 20 Elem- 10  1.03 1.01 1.01 1.01 Ex 21Elem- 12  1.01 1.00 1.00 1.00 Ex 22 Elem- — 1.00 1.00 1.00 1.00 Comp 12

It is seen from Table 22 that the spacing between the cathode electrodeand the substrate can be determined preferably in the range of not morethan 5 cm.

It is also seen from Table 23 that the spacing between the fins can bedetermined desirably in the range of 2 cm to 10 cm both inclusive.

The same was found to be applicable when the present invention wasapplied to fabrication of the i-layer.

APPARATUS EXAMPLE 2

Next shown is a deposit film forming apparatus for introducing differentgas species independently of each other through a plurality of gas inlettubes as a material gas introducing means.

FIG. 8A is a schematic cross-sectional view of the apparatus, takenalong the direction parallel to the conveying direction, to show thefeature in the discharge container of the present invention. FIG. 8B isa schematic cross-sectional view of the apparatus, taken along thedirection perpendicular to the conveying direction (a cross sectionalong 8B—8B in FIG. 8A). This example employs the cathode electrode withpartitions having the same structure as the cathode electrode example asshown in FIG. 1D.

In FIGS. 8A and 8B, the cathode electrode 8002 with partitions 8003 isset above the ground (anode) electrode 8004 as being electricallyinsulated by insulator 8009. As being supported by a plurality of magnetrollers not shown, the electroconductive beltlike member 8000 movesabove the cathode electrode and in the direction represented by an arrowwithout physical contact with the cathode electrode located thereunderand with the lamp heater located thereabove.

A doping gas or, a gas containing an additive is introduced throughceramic gas inlet tube 8007 a to the proximity of the surface of thebeltlike member. On the other hand, a film-forming gas such as silaneand a diluent gas such as hydrogen are introduced through ceramic gasinlet tube 8007 b, so disposed as to penetrate the cathode electrode, toregions relatively apart from the surface of the beltlike member.

The gases pass through the discharge space between the beltlike memberand the cathode electrode and then is evacuated by an unrepresentedvacuum pump from exhaust port 8006 through punching board 8010. Thematerial for the cathode electrode and anode electrode may be stainlesssteel, aluminum, or the like.

Discharge regions of glow discharge occurring with application of RFpower from an unrepresented RF power supply to the cathode electrodeinclude gaps between the plural partition electrodes 8003 being parts ofthe cathode electrode, and the space between the beltlike member and thecathode electrode, which are regions confined by the electroconductivebeltlike member located above.

The distance between the substrate and the cathode electrode isdetermined preferably in the range of approximately 5 or less cm, asdescribed above. Further, the spacing between the plural partitionelectrodes 8003 is determined preferably in the range of 2 cm to 10 cmboth inclusive.

This apparatus was used for forming the p-layer of single cell.According to observation of cross-sectional TEM images thereof,microcrystals were recognized in the p-layer.

What is claimed is:
 1. A deposition apparatus comprising a powerapplying electrode disposed in a plasma discharge space of a plasma CVDapparatus, the power applying electrode having a plurality of partitionswherein intervals of said partitions are between 2 cm and 10 cminclusive; and a surface area of the power applying electrode is greaterthan a surface area of the whole of a ground electrode.
 2. Thedeposition apparatus according to claim 1, wherein different gas speciesare introduced independently of each other through a plurality of gasinlet tubes.
 3. The deposition apparatus according to claim 1, whereinat least one tube of said plurality of gas inlet tubes is forintroducing a doping gas and/or a gas containing an additive to near thesubstrate and another pipe is for introducing a gas containing siliconand/or a diluent gas to a region apart from the substrate.
 4. Thedeposition apparatus according to claim 1, wherein said additive is oneselected from the group consisting of germanium, carbon, nitrogen, andoxygen.
 5. The deposition apparatus according to claim 1, wherein saidpartitions are of fins or blocks.
 6. The deposition apparatus accordingto claim 1, wherein said partitions are parallel to flow of a materialgas.
 7. The deposition apparatus according to claim 1, wherein saidpartitions are perpendicular to flow of a material gas.
 8. Thedeposition apparatus according to claim 1, wherein said power applyingelectrode is comprised of stainless steel or aluminum.
 9. The depositionapparatus according to claim 1, wherein a self-bias of said powerapplying electrode upon plasma discharge is a positive potentialrelative to the ground electrode.
 10. The deposition apparatus accordingto claim 1, wherein space between said power applying electrode and asubstrate is not more than 5 cm and said power applying voltage is notin contact with the substrate.
 11. A deposition apparatus comprising apower applying electrode disposed in a plasma discharge space of aplasma CVD apparatus, the power applying electrode having a plurality ofpartitions wherein the partitions have vents and are parallel to a flowof a material gas; and a surface area of the power applying electrode isgreater than a surface area of the whole of a ground electrode.
 12. Adeposition apparatus comprising a power applying electrode disposed in aplasma discharge space of a plasma CVD apparatus, the power applyingelectrode having a plurality of partitions wherein a cross section ofsaid partitions is of a chevron shape; and a surface area of the powerapplying electrode is greater than a surface area of the whole of aground electrode.